Vehicle suspension systems are used to absorb road load inputs and other vibrations to provide a smooth and comfortable ride. Vehicle suspension systems often include a stabilizer bar that is used to increase roll rigidity and improve steering stability. Typically, the stabilizer bar is connected to lower control arms, which are mounted to a wheel component, such as a knuckle. In this typical configuration, the stabilizer bar controls sway and provides a pull down force during turning maneuvers.
During a turn, a vehicle body has a tendency to roll to the outside of the turn. Suspension components on the outside of the turn are compressed while the suspension components on the inside of the turn are extended. The stabilizer bar helps to counter this motion by providing opposing input at each location. Thus, the stabilizer bar pushes up on collapsed components and compresses extended components during turning.
In order to provide a good ride quality it is desirable to control stiffness/compliance of the stabilizer bar. During turning maneuvers, it is desirable to increase the stiffness of the stabilizer bar to reduce the occurrence of vehicle rollover. However, if the stabilizer bar is too stiff, ride quality and handling characteristics can be compromised. Thus, it is desirable to have a stabilizer bar with variable stiffness to adjust for different driving conditions.
Different mechanisms for varying stiffness in a stabilizer bar have been proposed, including using variable clamping devices and solenoid controlled pin stops, for example. These mechanisms are often complex and expensive. Thus, there is a need for a simplified active control for selectively adjusting stiffness in a stabilizer bar.